Ceramic matrix composites (CMCs), including CMCs that are reinforced with fibers, were developed to alleviate damage tolerance issues of monolithic ceramics such as SiC ceramics and have become attractive for high temperature structural applications, such as in gas turbine engines. One type of fiber-reinforced CMCs that is particularly attractive for high temperature structural applications is reactive melt infiltrated fiber-reinforced CMCs (hereinafter “MI-CMCs”).
In MI-CMCs, a preform of fibers and matrix constituents is infiltrated with a metal which produces a ceramic matrix when reacting with the matrix constituents. SiC-based MI-CMCs, wherein the infiltrating metal is silicon or a silicon alloy and the matrix constituents are such that the resulting matrix is substantially SiC (e.g., SiC and/or C particulates), are particularly attractive for high temperature structural applications because of their high thermal conductivity, excellent thermal shock resistance, creep resistance, and oxidation resistance compared to other CMCs.
In gas turbine applications MI-CMC components are often subjected to loads above the matrix cracking stress of the components. The resulting cracks in the matrix portion of the components from such stresses act to decrease the stiffness and oxidation resistance of the MI-CMC composite, and can lead to premature failure of the MI-CMC component. Further, temporary overstress conditions, such as from dropped parts or tools, can occur during MI-CMC component fabrication, transportation and/or installation and also can result in matrix cracks. General wear may also shorten the lifespan of MI-CMC components. Effective methods of repair are therefore needed, so that MI-CMC components that exhibit cracks or other damage can be returned to a suitable state for use rather than needing to be replaced.
One option for repairing MI-CMC components is to fill cracks or refurbish other worn or damaged aspects by performing a MI process on the damaged MI-CMC component. However, an undesirable consequence of such a repair process may be that material such as Si gets lost from original portions of the MI-CMC component, such as by volatization during an MI process or seepage of silicon into capillaries of an additional MI-CMC segment added to the component being reworked. Thus, a need exists for methods and related configurations, components and assemblies for repairing matrix cracks in MI-CMC components to restore them to a usable condition without loss of Si or other material during repair.